DNV 2.7 1 OFFSHORE CONTAINERS

Prévia do material em texto

STANDARD FOR CERTIFICATION
No. 2.7-1
OFFSHORE CONTAINERS
APRIL 2006
This Standard for Certification includes all amendments and corrections up to November 2008.
DET NORSKE VERITAS
FOREWORD
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erty and the environment, at sea and onshore. DNV undertakes classification, certification, and other verification and consultancy
services relating to quality of ships, offshore units and installations, and onshore industries worldwide, and carries out research
in relation to these functions.
Standards for Certification
Standards for Certification (previously Certification Notes) are publications that contain principles, acceptance criteria and prac-
tical information related to the Society's consideration of objects, personnel, organisations, services and operations. Standards
for Certification also apply as the basis for the issue of certificates and/or declarations that may not necessarily be related to clas-
sification. 
A list of Standards for Certification is found in the latest edition of Pt.0 Ch.1 of the ”Rules for Classification of Ships” and the
”Rules for Classification of High Speed, Light Craft and Naval Surface Craft”.
The list of Standards for Certification is also included in the current “Classification Services – Publications” issued by the Society,
which is available on request. All publications may be ordered from the Society’s Web site http://webshop.dnv.com/global/.
The Society reserves the exclusive right to interpret, decide equivalence or make exemptions to this Standard for Certification.
Errata 2008-11-26
References to ‘DNV Rules for Certification of Lifting Appliances’ have been amended to read ‘DNV Standard for Certification
No. 2.22 Lifting Appliances’.
Comments may be sent by e-mail to rules@dnv.com
Comprehensive information about DNV and the Society's services is found at the Web site http://www.dnv.com
© Det Norske Veritas
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Standard for Certification - 2.7-1, April 2006
Page 3
Introduction
This Standard for Certification was first published in May,
1989 as "DNV Certification note 2.7-1 Offshore Freight Con-
tainers". It was prepared because other regulations at the time,
whether international codes, national requirements or rules
published by Det Norske Veritas, did not specifically cover
offshore containers. A revised Certification Note was issued in
May 1995. The basic strength and design requirements from
the original edition were retained.
Many other standards, codes and regulations exist for contain-
ers, container-like units and related types of equipment. Inter-
national standards, codes and regulations considered relevant
have been taken into account when preparing this Standard for
Certification. The most important of these are IMO's circular
MSC/Circ.860 and EN 12079. In 1991 the European Commit-
tee for Standardisation, CEN, started developing a European
Standard (EN) on offshore containers. Technical committee
CEN TC 280 prepared EN 12079, which was issued in 1999,
and a revised edition will be issued in 2006. The requirements
for design, testing and production of offshore containers in EN
12079 are directly based on DNV Standard for Certification
2.7-1. The relationship between this Standard for Certification
and other standards, codes and regulations is outlined in sub-
chapter 1.2.
The Standard for Certification is concerned with certification
of all types of offshore containers as transport units. The three
typical phases of transport are: shoreside (e.g. by fork lift
truck), by supply vessel and lifting to and from offshore instal-
lations. The Standard for Certification includes design require-
ments related to all three phases. 
Under conditions in which offshore containers are often trans-
ported and handled, the "normal" rate of wear and tear is high,
and damage necessitating repair will occur. However, contain-
ers designed and certified according to this Standard for Certi-
fication should have sufficient strength to withstand the
normal forces encountered in offshore operations, and not suf-
fer complete failure even if subject to more extreme loads.
Changes in the 2006 edition
The Standard for Certification has been extensively revised,
with changes in all sections. However, the basic design and
strength requirements have not been changed, with the excep-
tion of lifting sets. Detailed requirements, interpretations and
guidances have been added throughout the standard and in the
new appendices. Some requirements have been changed to
align with the new EN 12079. New material requirements
have been introduced for offshore containers that will only be
certified for use in temperate climates. Many editorial changes
have been made and the Appendices have been renumbered.
The most important changes are:
— Section 1 has been extended to include detailed references
to other container standards and regulations.
— The requirements for materials have been taken out of the
design section and moved to a separate Section 3.
— In the design section (now Section 4) there are several
changes and additions, including protection on the top of
open containers, allowable stresses in aluminium, clear-
ances in padeye holes, requirements for fork pockets, test-
ing of long containers with fork lift, and many additional
guidances and notes.
— In Section 5 (Production) detailed requirements for NDE
have been added and the amount of production testing has
been reduced.
— Section 8 for lifting sets has been extensively revised. Ref-
erence standards have been added, a new calculation
method has been introduced, detailed requirements for
sling and component certificates have been added and the
marking tags on lifting slings have been revised. 
— In Section 9 the schedule for period examination and tests
have been changed.
— A new Appendix C has been added with guidelines and 
examples on strength calculations.
— A new appendix D has been added with guidance on de-
sign and calculations of padeyes.
— Appendix E on calculations of lifting sets has been greatly
extended.
— IMO's circular on offshore containers, MSC/Circ. 860 has
been added at Appendix I. 
— Existing Annexes 1 and 2 will now be included in the same
booklet as the rest of the standard. 
— A new Annex 3 concerning containers for temperate cli-
mates has been introduced. Containers certified to
Annex 3 have higher design temperature than required by
the main requirements of this Standard for Certification,
but are otherwise identical to standard offshore containers.
Consequences:
— Existing offshore containers that DNV have been certified
according to previous versions of Standard for Certifica-
tion 2.7-1 will also comply with the new standard. Re-
certification is generally not deemed necessary. However,
on some containers the new requirements for lifting sets in
Section 8 may give higher requirements for slings and or
shackles.
— Containers certified to this Standard for Certification will
comply with the requirements of MSC/Circ.860.
— Containers certified to this Standard for Certification will
also comply with the requirementsin the new EN12079
parts 1 and 2, and certification to this standard can be in-
cluded at no extra cost.
DET NORSKE VERITAS
Standard for Certification - 2.7-1, April 2006
Page 4
DET NORSKE VERITAS
Standard for Certification - 2.7-1, April 2006
Page 5
CONTENTS
1. GENERAL .............................................................. 8
1.1 Scope .........................................................................8
1.2 Relationship with other standards, codes and 
regulations ................................................................8
1.2.1 The International Maritime Organization (IMO) ............... 8
1.2.2 ISO standard freight containers (ISO Containers).............. 8
1.2.3 European Standard EN 12079 ........................................... 8
1.2.4 Standard for Certification 2.7-2 – Offshore service 
containers............................................................................ 8
1.2.5 Units for transportation offshore ........................................ 8
1.2.6 Regulations for Lifting Appliances .................................... 9
1.3 National authorities .................................................9
1.4 Definitions ................................................................9
1.4.1 Offshore container .............................................................. 9
1.4.2 Freight container................................................................. 9
1.4.3 Units for transportation offshore ........................................ 9
1.4.4 Permanent equipment ......................................................... 9
1.4.5 Primary Structure................................................................ 9
1.4.6 Secondary Structure.......................................................... 10
1.4.7 Prototype........................................................................... 10
1.4.8 Owner ............................................................................... 10
1.4.9 Lifting set.......................................................................... 10
1.4.10 Assembly secured shackle ................................................ 10
1.5 List of symbols .......................................................10
2. APPROVAL AND CERTIFICATION 
PROCEDURES .................................................... 10
2.1 General ...................................................................10
2.2 Approval.................................................................11
2.2.1 Approval Schemes ............................................................ 11
2.2.2 Approval to other standards.............................................. 11
2.2.3 Documents for approval and information......................... 11
2.2.4 Design Review.................................................................. 11
2.3 Certification ...........................................................11
2.3.1 Survey and certification.................................................... 11
2.3.2 Testing and inspection ...................................................... 12
2.4 Certification of existing containers ......................12
2.5 Maintenance of certificate ....................................12
2.6 Summary of procedures........................................12
2.6.1 Procedure for individual (case-by-case) approval and 
certification ....................................................................... 12
2.6.2 Procedure for type approval and certification .................. 12
2.6.3 Procedure for design assessment for type approval and 
certification ....................................................................... 12
3. MATERIALS........................................................ 13
3.1 Steel.........................................................................13
3.1.1 General.............................................................................. 13
3.1.2 Rolled, forged and cast steels in offshore container 
structures........................................................................... 13
3.2 Aluminium .............................................................14
3.3 Non-metallic materials ..........................................14
3.4 Material certificates ..............................................14
4. DESIGN ................................................................ 14
4.1 General ...................................................................14
4.1.1 Structural design ............................................................... 15
4.1.2 Stability against tipping .................................................... 15
4.1.3 Protruding parts and top protection .................................. 15
4.1.4 Design temperature........................................................... 15
4.2 Structural strength ...............................................15
4.2.1 Allowable stresses ............................................................ 15
4.2.2 Load distribution............................................................... 16
4.2.3 Lifting loads...................................................................... 16
4.2.4 Impact loads...................................................................... 16
4.3 Welding .................................................................. 17
4.3.1 Welding of padeyes .......................................................... 17
4.3.2 Welding of other primary structure .................................. 17
4.4 Design Details ........................................................ 17
4.4.1 Padeyes ............................................................................. 17
4.4.2 Intermediate cargo decks .................................................. 17
4.4.3 Stacking and stacking fittings........................................... 18
4.4.4 ISO-corner fittings............................................................ 18
4.4.5 Floor.................................................................................. 18
4.4.6 Fork lift pockets................................................................ 18
4.4.7 Container walls ................................................................. 18
4.4.8 Doors and hatches............................................................. 18
4.4.9 Internal securing points .................................................... 18
4.4.10 Tugger points ................................................................... 19
4.4.11 Equipment......................................................................... 19
4.4.12 Coating and corrosion protection ..................................... 19
4.5 Tank containers and bulk containers.................. 19
4.5.1 Tank containers ................................................................ 19
4.5.2 Tank containers for dangerous goods............................... 19
4.5.3 Containers for bulk solids................................................. 19
4.5.4 Bulk Containers for solid dangerous goods...................... 20
4.6 Prototype testing ................................................... 20
4.6.1 Introduction ...................................................................... 20
4.6.2 Test equipment and calibration......................................... 20
4.6.3 Lifting tests ....................................................................... 20
4.6.4 Vertical impact test ........................................................... 21
4.6.5 Other tests ......................................................................... 21
5. PRODUCTION .................................................... 21
5.1 General ................................................................... 21
5.2 Primary structure ................................................. 21
5.2.1 Approved Welders ............................................................ 21
5.2.2 Welding procedures..........................................................22
5.2.3 Inspection of welds........................................................... 22
5.2.4 NDE procedures and NDE operators................................ 22
5.3 Secondary structure.............................................. 22
5.4 Production testing ................................................. 22
5.4.1 Lifting test......................................................................... 22
5.4.2 Weatherproofness testing ................................................. 23
5.5 Production documentation ................................... 23
5.6 Inspection and certification.................................. 23
6. MARKING ........................................................... 23
6.1 Safety marking ...................................................... 23
6.2 Identification and Certification Markings.......... 24
6.3 Information Markings .......................................... 24
6.4 Marking of Lifting Set .......................................... 24
6.5 Other Marking ...................................................... 24
7. PLATING OF CONTAINERS ........................... 24
7.1 General ................................................................... 24
7.2 Data Plate............................................................... 24
7.3 Inspection plate ..................................................... 25
8. LIFTING SETS.................................................... 25
8.1 General requirements ........................................... 25
8.2 Approval and certification of lifting sets............. 25
8.3 Design of lifting sets .............................................. 25
8.3.1 Dimensions and Strength of Lifting Sets.......................... 26
8.3.2 Lifting set components ..................................................... 27
8.4 Materials ................................................................ 27
8.5 Certificates for lifting sets and components ....... 28
DET NORSKE VERITAS
4.2.5 Minimum material thickness ............................................ 17 8.5.1 Sling certificates ............................................................... 28
Standard for Certification - 2.7-1, April 2006
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8.5.2 Component certificates .....................................................28
8.6 Marking of lifting sets........................................... 28
9. PERIODIC EXAMINATION, TESTS AND 
REPAIRS .............................................................. 29
9.1 General ................................................................... 29
9.2 Inspection, test and repairs on containers ......... 29
9.2.1 Schedule of examination and tests ....................................29
9.2.2 Visual inspection...............................................................29
9.2.3 Non-destructive testing .....................................................30
9.2.4 Repairs and modifications of containers...........................30
9.2.5 Marking of the inspection plate ........................................30
9.3 Inspection, test and repairs on lifting sets........... 30
9.3.1 Schedule of examination and tests ....................................30
9.3.2 Load testing of chain sling legs ........................................30
9.3.3 Non-destructive examination of sling components except 
wire rope legs ....................................................................30
9.3.4 Visual inspection of the lifting set ....................................30
9.3.5 Chain and wire rope slings and components.....................30
9.3.6 Shackles ............................................................................31
9.3.7 Marking of the lifting set tag ............................................31
9.4 Inspection, test and repairs on tank containers 31
9.5 Inspection reports ................................................. 31
APP. A
LIST OF REFERENCES.................................................. 32
APP. B
EXAMPLE OF OFFSHORE CONTAINER .................. 34
APP. C
GUIDELINES AND EXAMPLES ON STRENGTH 
CALCULATIONS ............................................................. 35
APP. D
DESIGN OF PADEYE ...................................................... 37
APP. E
CALCULATIONS OF LIFTING SETS.......................... 38
APP. F
EXAMPLE OF DROP TEST ........................................... 42
APP. G
CERTIFICATE FOR OFFSHORE CONTAINER........ 43
APP. H
DNV EMBLEM FOR OFFSHORE CONTAINERS ..... 45
APP. I
MSC/CIRC.860 .................................................................. 46
APP. J
CERTIFICATE FOR OFFSHORE CONTAINER 
LIFTING SLINGS – EXAMPLE..................................... 51
APP. K
CERTIFICATE FOR LIFTING SET COMPONENTS* 
FOR OFFSHORE CONTAINERS – EXAMPLE ......... 52
ANNEX 1 
TYPE APPROVAL OF LIFTING SETS FOR 
1. INTRODUCTION ............................................... 53
2. SCOPE .................................................................. 53
3. GENERAL............................................................ 53
3.1 Documentation to be submitted........................... 53
3.1.1 Documentation for type approval of lifting slings............53
3.1.2 Documentation for type approval of lifting set 
components .......................................................................53
3.1.3 General documentation from the manufacturer ................53
3.2 Validity................................................................... 53
3.3 Renewal.................................................................. 53
4. DESIGN REQUIREMENTS .............................. 54
5. MATERIALS AND MATERIAL TESTING.... 54
6. PROTOTYPE TESTING.................................... 54
7. MARKING AND TRACEABILITY.................. 54
8. REQUIREMENTS RELATED TO 
MANUFACTURERS .......................................... 54
9. TYPE APPROVAL CERTIFICATE................. 54
10. PRODUCTION AND CERTIFICATION......... 55
10.1 Production testing................................................. 55
10.2 Lifting set certificate............................................. 55
10.3 Certificates for Lifting Set Components............. 55
ANNEX 2 
APPROVAL PROGRAMME FOR TEST 
FACILITIES ENGAGED IN LOAD TESTING AND 
NDT INSPECTION OF OFFSHORE 
CONTAINERS ..........................................................56
1. GENERAL............................................................ 56
1.1 Scope ...................................................................... 56
1.2 Objective................................................................ 56
1.3 Extent of engagement ........................................... 56
1.4 Validity................................................................... 56
2. REQUIREMENTS TO SUPPLIER................... 56
2.1 Submission of documents ..................................... 56
2.2 Quality assurance system..................................... 56
2.3 Qualification of personnel ................................... 56
2.4 Supervisor.............................................................. 57
2.5 Operators............................................................... 57
2.6 Personnel records.................................................. 57
2.7 Equipment ............................................................. 57
2.8 Procedures and instructions ................................ 57
2.8.1 Lifting tests .......................................................................57
2.8.2 Vertical impact test ...........................................................57
2.8.3 Other tests .........................................................................58
2.8.4 Non-destructive examination ............................................58
2.9 Administrative procedures .................................. 58
2.10 Verification............................................................ 582.11 Sub-contractors..................................................... 58
2.12 Reporting ............................................................... 58
2.12.1 Contents of reports:...........................................................58
2.12.2 Prototype or production tests ............................................58
DET NORSKE VERITAS
OFFSHORE CONTAINERS ...................................53 2.12.3 Tests on existing containers ..............................................58
Standard for Certification - 2.7-1, April 2006
Page 7
3. REPAIRS ON CONTAINERS IDENTIFIED AS 
A RESULT OF LOAD TESTS AND OR NDT . 58
3.1 General ...................................................................58
4. APPROVAL PROCEDURES ............................. 58
4.1 Review of documentation......................................58
4.2 Initial audit.............................................................58
4.3 Special procedures related to control of supplier's 
relationship with the parent company.................58
4.4 Certificate of approval ..........................................59
4.5 Renewal of approval..............................................59
5. INFORMATION ON ALTERATION TO THE 
CERTIFIED SERVICE 
OPERATION SYSTEM ...................................... 59
5.1 Alteration ...............................................................59
6. CANCELLATION OF THE CERTIFICATE OF 
APPROVAL ......................................................... 59
6.1 Right to cancel ....................................................... 59
6.2 Information............................................................ 59
6.3 Re-approval ........................................................... 59
7. REFERENCES..................................................... 59
ANNEX 3 
OFFSHORE CONTAINERS FOR USE IN 
TEMPERATE CLIMATES ONLY ........................60
1. INTRODUCTION................................................ 60
2. AREA .................................................................... 60
3. DESIGN TEMPERATURE ................................ 60
4. MARKING ........................................................... 60
5. DATA PLATE ...................................................... 60
DET NORSKE VERITAS
Standard for Certification - 2.7-1, April 2006
Page 8
1. General
1.1 Scope
This Standard for Certification applies for transport related re-
quirements for offshore containers with respect to design,
manufacture, testing, certification, marking and periodic in-
spection. 
The Standard for Certification covers the container structure
and any permanent equipment for handling, filling, emptying,
refrigerating, heating and safety purposes.
The intention is that offshore containers shall meet the follow-
ing requirements:
— Be safe in use with regard to:
— lives
— environment
— hazard to the vessel/installation
Be suitable for repeated use through choice of:
— material
— protection
— ease of repair and maintenance.
The requirements in this Standard for Certification are based
on a number of assumptions regarding the handling and oper-
ation of offshore containers:
— They are lifted individually by crane hook attached to top
link of lifting set
— They are not lifted by spreaders or using ISO container fit-
tings
— They can be lifted anywhere (world wide) by any crane
with sufficient capacity and speed
— For containers only approved for limited operation area
(Temperate Climate) see Annex 3
— They are only stacked if they are designed for this.
— They are stacked only onshore or on offshore installations.
Not to be stacked during transport on ships.
— Cargo or loose installations are properly secured in the
container.
— The container is designed to give adequate protection to its
cargo or to installations inside. 
— They are handled according to IMO’s “Code of safe prac-
tice for supply vessels”.
— Handling and operation is in accordance with local regula-
tions.
The Society may approve alternative solutions that are found
to represent an overall safety standard equivalent to the re-
quirements in this Standard for Certification. Such approval
may be revoked if subsequent information indicates that the
chosen alternative is not satisfactory.
When the word "container" is used throughout the Standard for
Certification, it means an offshore container.
Use of the word “shall” implies a mandatory requirement when
seeking the Society’s approval. Use of the word “should” im-
plies a recommended approach, where comparable solution
may also be acceptable.
The passages throughout this Standard for Certification
marked "Guidance" and “Note” are not to be taken as require-
ments by Det Norske Veritas. Such Guidance and Notes are in-
tended as practical advice and information for the designer,
manufacturer or operator.
This Standard for Certification often refers directly to various
standards (EN, ISO etc.), or to “other recognised standard”.
Recognised standard means a standard found acceptable by the
1.2 Relationship with other standards, codes and 
regulations
1.2.1 The International Maritime Organization (IMO)
IMO has issued both the International Convention for Safe
Containers, CSC, and the International Maritime Dangerous
Goods code, IMDG. Both of these are mandatory international
regulations. IMO has recognised that the CSC convention is
not directly applicable for offshore containers that are handled
in open seas, and has issued a circular (MSC/Circ.860) with
guidelines on certification of offshore containers. The IMDG
code also requires that containers and portable tanks that are
handled in open seas should be certified for this purpose.
Containers certified to this Standard for Certification also
comply with MSC/Circ.860, and this will be referenced in the
certificates. The circular is reproduced at Appendix I.
IMO has also issued the Code of safe practice for the carriage
of cargoes and persons by offshore supply vessels (OSV code)
which includes guidelines for handling, stowage and securing
of cargoes.
1.2.2 ISO standard freight containers (ISO Containers)
Containers that are intended for sea transport on container
ships are normally designed according to an applicable part of
ISO 1496. Containers that are certified to CSC are in general
also designed as ISO containers.
Offshore containers designed and certified according to this
Standard for Certification can also be designed and certified
according to CSC And ISO 1496.
1.2.3 European Standard EN 12079 
(At date of writing: new version only available as prEN 12079)
The European Standard EN 12079 “Offshore containers and
associated lifting sets” consists of 3 parts, see Table 1-1. 
Offshore Containers and lifting sets certified to this Standard
for Certification also comply fully with prEN12079 parts 1 and
2 respectively, and this may be referenced in the certificates.
1.2.4 Standard for Certification 2.7-2 – Offshore service 
containers
When an offshore container is designed and equipped to be
placed onboard a fixed or floating offshore installation to per-
form specific services, it may be subject to regulations apply-
ing on the installation and to the area where it is placed.
Standard for Certification 2.7-2 “Offshore Service Containers”
covers containers designed for such requirements.
1.2.5 Units for transportation offshore
Many portable units intended for offshore use are not contain-
ers as defined in this Standard for Certification. However,
there is often a need for verification and certification of such
units. DNV has therefore prepared a new Standard for Certifi-
cation 2.7-3 for Portable Offshore Units with requirements for
design, manufacture, testing etc. for portable units up to 50 000
kg. 
Offshore Units certified to that Standard for Certification are
Table 1-1 
EN 12079 
part:Title Equivalent sections in 
Standard for 
Certification 2.7-1
Part 1 Offshore containers – 
design, manufacture and 
marking
Sec. 1, 3, 4, 5, 6, 7
Part 2 Lifting sets – Design, 
manufacture and marking
Sec. 8 
Part 3 Periodic inspection, 
examination and testing
Sec. 9
DET NORSKE VERITAS
Society. not intended to carry cargoes as their primary function, but
Standard for Certification - 2.7-1, April 2006
Page 9
may carry loose equipment that is related to their intended
service.
The main difference between Offshore containers and “Units
for transportation offshore” is: For such units, their fitness for
use must be assessed for each design type, and may have to be
considered for each transport event. Operational restrictions
may be given in the certificate, or it may be required that the
operator evaluate their suitability for each event. 
1.2.6 Regulations for Lifting Appliances
Offshore containers are not lifting equipment as defined by
ILO, by the European Community’s Machinery Directive or
by DNV Standard for Certification No. 2.22 Lifting Applianc-
es. Instead they are considered to be cargo units as defined in
these codes and directives.
However, requirements from these regulations and standards
have been taken into account in the requirements in this Stand-
ard for Certification, e.g. in the intervals for periodic surveys.
1.3 National authorities
In cases where National Authorities have stricter requirements
than this Standard for Certification, these may be incorporated
in the certification procedures.
Note:
Some National Authorities may consider offshore containers to
be lifting equipment.
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1.4 Definitions
1.4.1 Offshore container
An offshore container is a portable unit with a maximum gross
mass not exceeding 25 000 kg, for repeated use in the transport
of goods or equipment, handled in open seas, to, from or be-
tween fixed and/or floating installations and ships.
An offshore container comprises permanently installed equip-
ment, see 1.4.4.
Note:
Other permanent or loose equipment will not be covered by the
certification unless specially agreed. However, supporting struc-
ture for heavy equipment, machinery, etc. will be approved ac-
cording to 4.4.11.
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Offshore containers are also defined by the requirements
throughout this Standard for Certification. Refer to definitions
of primary and secondary structure below and in 4.1. 
Units for offshore lifting that are intended for installation and
not for repeated transport are not considered to be containers.
Likewise, units that do not have an outer framework with
padeyes are not considered to be containers. Hence, these units
are not covered by Standard for Certification 2.7-1. (See how-
ever the definition of waste skip in 1.2.2.) Many such portable
units may be eligible for certification according to DNV’s
Standard for Certification for Portable Offshore Units1.
Offshore containers may be divided into 3 main categories:
a) Offshore freight container:
Offshore container built for the transport of goods. Exam-
ples of offshore freight containers:
— general cargo container: a closed container with doors
— cargo basket: an open top container for general or
special cargo (e.g. pipes, risers)
— tank container: a container for transport of dangerous
or non-dangerous fluids
— bulk container; container for transport of solids in
— special container; container for transport of special
cargo (e.g. garbage compactors, equipment boxes,
bottle racks).
b) Offshore service container: 
Offshore container built and equipped for a special service
task, mainly as temporary installation. (Examples are, lab-
oratories, workshop, stores, power plants, control stations,
wireline units).
c) Offshore waste skip
An open or closed offshore container used for the storage
and removal of waste. Normally constructed from flat
steel plates forming the load bearing sections of the con-
tainer, bracing in the form of steel profiles, e.g. channel or
hollow section, being fitted horizontally around sides and
ends. Waste skips may be open or have loose or hinged
covers 
In addition to the pad eyes for the lifting set these contain-
ers may also have side mounted lugs suitable for attach-
ment of the lifting equipment mounted on a skip lift
vehicle.
1.4.2 Freight container
Re-usable transport container, used for international traffic and
designed to facilitate the carriage of goods by one or more
modes of transport (including marine) without intermediate re-
loading. See DNV "Rules for Certification of Freight Contain-
ers, 1981". Also known as CSC Containers or ISO Containers.
1.4.3 Units for transportation offshore
Portable unit or package with a maximum gross mass not ex-
ceeding 50 000 kg, for repeated or single use with a primary
service function, handled in open seas, to, from or between
fixed and/or floating offshore installations and ships. Units of
this type are not considered to be offshore containers.
1.4.4 Permanent equipment
Equipment that is attached to the container and which is not
cargo. 
Note:
May include lifting sets, additional fittings for handling and se-
curing, filling, emptying, cooling and heating, intermediate
decks, securing points, garbage compactors, etc.
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1.4.5 Primary Structure
Load carrying and supporting frames and load carrying panels. 
Primary structure includes the following structural compo-
nents:
— Load carrying and supporting frames
— Load carrying panels (floor, ‘tweendecks)
— Fork lift pockets
— Pad eyes
— Supporting structures for tanks
— Supports for heavy equipment
— Corner/knee brackets.
Primary structure is divided into two sub-groups:
a) Essential and non-redundant primary structure are the
main structural elements which transfer the resulting cargo
load to the crane hook or fork lift truck (i.e. forming the
load path from the payload to the lifting sling), and will at
least include:
— top and bottom side rails
— top and bottom end rails
— corner posts
DET NORSKE VERITAS
bulk — pad eyes
Standard for Certification - 2.7-1, April 2006
Page 10
— fork lift pockets.
Other primary structure may also be considered essential
and or non-redundant.
b) Non-essential primary structure are e.g. floor plates and
other structural elements for which the main function is
other than described in a). Deflector plates, stacking fit-
tings and end plates on hollow section are considered to be
in this category. This sub-group also includes protective
frame members.
Side and roof panels (including corrugated panels) are not con-
sidered to be part of the primary structure and shall not be tak-
en into account when evaluating the strength of the container.
For waste skips the requirements in 4.1.1 apply.
1.4.6 Secondary Structure
Parts that are not considered as load carrying for the purposes
of the design calculations. Secondary structure includes the
following components:
— Doors, wall and roof panels, covers on skids
— Panel stiffeners and corrugations
— Structural components used for tank protection only
— Internal securing points
1.4.7 Prototype
An equipment item, considered to be representative for the
production and the product to be approved, used for prototype
testing. The prototype may either be manufactured especially
for type testing or selected at random from a production series.
If manufactured specially, it is expected that the tools and the
production process are comparable to those to be used for sub-
sequent production.
1.4.8 Owner
The legal owner of the offshore container or a delegated nom-
inee.
1.4.9 Lifting set
Items of integrated lifting equipment used to connect the off-
shore container to the lifting appliance. This can comprise sin-
gle or multi leg slings(with or without a top leg) and shackles,
whether assembly secured or not.
1.4.10 Assembly secured shackle
Shackle fitted to a sling leg and secured by a seal or similar de-
vice, so as to signal, unambiguously, whether or not the shack-
le has been exchanged.
Note 1:
Shackles that are captive in the thimbles are also considered as
assembly secured.
---e-n-d---of---N-o-t-e---
 
Note 2:
Shackles that are assembly secured, i.e. can not be separated
from the lifting sling, are considered to be part of the lifting sling.
See 9.3.
---e-n-d---of---N-o-t-e---
 
1.5 List of symbols
R = Rating or maximum gross mass of the offshore con-
tainer including permanent equipment and its cargo,
Note:
The mass of the lifting set is not included in R because the lifting
set is often not available at the time of certification and because
it may be replaced during the lifetime of the container.
---e-n-d---of---N-o-t-e---
 
T = Tare mass. Mass of the empty container including
any permanent equipment but excluding cargo and
lifting set, in kg;
P = Payload. The maximum permissible mass of cargo
which may safely be transported by the container, in
kg. (P = R- T)
S = The mass of the lifting set
F = Design load, in N
L = Length of container, in mm
Re = Specified minimum yield stress at room tempera-
ture, in N/mm2.
Rm = Specified minimum tensile strength at room tem-
perature, in N/mm2.
Rp 0.2 = 0.2% proof stress at room temperature, in N/mm2.
RSL = Resulting Sling Load on padeyes, in N.
TD = The design temperature is a reference temperature
used for the selection of steel grades used in off-
shore containers and equipment. 
g = Standard acceleration of gravity (~ 9.81 m/s2).
ln = Nominal length of structural member, in mm
n = Number of sling legs
t = Material thickness, in mm.
v = Angle of sling leg from vertical in degrees
y = Deflection of structural member, in mmσe = The von Mises equivalent stress, in N/mm2.Ψ = Load factor
WLL = Working Load Limit, in tonnes. Maximum mass
that a lifting component is authorized to sustain in
lifting service
Note 1:
The WLL for lifting components that is specified in standards,
product specifications, etc. is normally the WLL for general lift-
ing service. For the special application of lifting sets fitted to off-
shore containers, the WLL is enhanced as described in Section.
8. 
---e-n-d---of---N-o-t-e---
 
Note 2:
The term "Safe Working Load, SWL" is not used in this Standard
for Certification. This term is not clearly defined for containers
and should, therefore not be used when referring to offshore con-
tainers. The term “Working Load Limit, WLL” is only used for
lifting sets, not for containers.
---e-n-d---of---N-o-t-e---
 
2. Approval and Certification Procedures
2.1 General
Offshore containers designed, manufactured, tested and
marked in compliance with the following requirements may be
certified by Det Norske Veritas. At the end of the verification
process a product certificate is issued by the Society and the
Society's numbered certification emblem is affixed to the con-
tainer.
Certification consists of the following steps:
— Design review
— Inspection and testing of prototype
— Production inspection and testing
— Issuance of certificates
An application for approval and certification should be sent to
DET NORSKE VERITAS
in kg; but excluding the lifting set the local DNV office who will forward this to the approval of-
Standard for Certification - 2.7-1, April 2006
Page 11
fice. The Application shall include:
— Short description of the container type(s) (size, function,
special features, etc.)
— Specification of standards and regulations to be covered
— Preferred type of approval scheme (see 2.2.1)
— Place of manufacture (if applicable)
— If individual approval is sought: the number of containers
to be manufactured.
2.2 Approval
2.2.1 Approval Schemes
If a manufacturer plans to build only one container, or a single,
limited batch of containers, the Society may give an individual
(case-by-case) approval valid for that batch only. The manu-
facturer must specify the number of containers to be covered
by the approval.
If series production is intended, or if further orders for the same
container design is expected in the future, type approval is rec-
ommended. Type Approval Certificates are normally issued to
the manufacturer of the container. If containers are made by a
manufacturer on behalf of the owner of a design type, both the
owner of the design type and the manufacturer will be listed in
the Type Approval Certificate.
If a designer/design company wishes to obtain an approval
certificate for a container design, either because they do not
manufacture themselves, or because it will be built at a later
date, the Society may issue a “Design Assessment for Type
Approval Certificate”. When the container design is built, it
shall be type tested and a Type Approval Certificate may be is-
sued to the manufacturer. If the manufacturer is a licensee, the
Type Approval Certificate will refer to the designer/design
company and to the Design Assessment for Type Approval
Certificate. If several licensees shall make containers of the
same design type, type testing shall normally be carried out at
each manufacturing plant.
Lifting sets for offshore containers may be type approved ac-
cording to Annex 1 to this Standard for Certification, “Type
Approval of Lifting Sets for Offshore Containers”.
DNV type approvals are listed in DNV Exchange on DNV’s
web site www.dnv.com
2.2.2 Approval to other standards
Offshore containers that are certified to this Standard for Cer-
tification will also comply with the guidelines in IMO’s circu-
lar MSC/Circ. 860. and with EN 12079 parts 1 and 2
respectively. Therefore these codes will normally be listed in
the Type Approval and Offshore Container certificates.
Offshore tank containers for dangerous goods shall be certified
according to the IMDG Code in addition to certification to
DNV 2.7-1.
Upon request, or if considered a necessary part of the
certification needed for a container, the Society may also cer-
tify offshore containers to other international or national
standards or regulations.
2.2.3 Documents for approval and information
For design review, the following documentation shall be sub-
mitted to an approval office through the local DNV offices in
ample time before manufacturing:
For approval, in triplicate:
— Plans showing arrangement, dimensions, maximum gross
mass, payload, scantlings of strength members, sling an-
gle, pad eyes and design details as well as materials to be
used Material standards should be specified.
— Particulars of joining methods (welding, bolted or riveted
connections). Welds to be indicated with welding symbols
For information (1 copy):
— Design calculations if available, including lifting set cal-
culations.
— Other documentation as required for special purpose con-
tainers or for special equipment.
Note 1:
If the application with documentation is sent by e-mail the docu-
mentation should by in Adobe® PDF format. The drawings and
documentation should be enclosed in a limited number of files
correctly formatted for printing.
---e-n-d---of---N-o-t-e---
 
Note 2:
The Society always verifies the strength of a container, and this
often includes strength calculations performed by the Society.
However, calculations to optimise the design will not be per-
formed by the Society.
---e-n-d---of---N-o-t-e---
 
Documentation to be presented to the local DNV Office at-
tending surveyor:
— Information about welders’ qualification
— Information about welding procedures 
— Information about NDT operators
— Particulars of corrosion protection and painting (type, ap-
plication, dry film thickness)
— Plating and marking
2.2.4 Design Review
This implies a reviewof:
— Strength of structure, including design details
— Material specifications
— Welding and other joining methods
— Lifting set
— Supporting structures for other permanent equipment
In cases where experience and/or other findings show that
safety hazards may arise in connection with items not covered
directly by the existing requirements, DNV may decide to lay
down at any time supplementary requirements to maintain the
overall safety standard.
DNV’s computer program “OffCon” may be used as a help to
do rule check calculations.
2.3 Certification
2.3.1 Survey and certification
Before production starts, the Society should verify that the
manufacturer has qualified welders and approved welding pro-
cedures, and that they are capable of manufacturing the con-
tainers.
Production shall be carried out according to the manufacturer’s
quality plan. During production, the Society will normally per-
form inspections in accordance with Section 5.
Alternatively, certification may be based on the Society's sur-
veillance of the manufacturer's quality assurance system. On
the basis of this system, the terms of survey and testing and the
frequency of attendance by a surveyor may be defined in a
Manufacturing Survey Arrangement (MSA). 
An MSA is an agreement in the form of a document stating the
role of Det Norske Veritas and the manufacturer in connection
with Manufacturing Survey and certification for a specific
range of materials/components. 
For each container produced, a product certificate, "Offshore
Container Certificate" (Form No. 49.07a, see Appendix G)
will be issued by a Surveyor from the Society. The DNV sur-
DET NORSKE VERITAS
to a recognised standard. veyor need only fill in and sign the front page of the certificate
Standard for Certification - 2.7-1, April 2006
Page 12
form at the time of delivery, If other information is available;
he may also include this on page 2 of the certificate.
Note:
Since the lifting set is often not delivered from the container
manufacturer, and normally will be replaced during the lifetime
of a container, the certificate need not include the lifting set. 
---e-n-d---of---N-o-t-e---
 
For tank containers for dangerous goods, DNV’s Certificate
for tank container or portable tank (Form 49.04a) shall be is-
sued in addition to the offshore container certificate. The 2
certificates shall both have the same certificate number.
2.3.2 Testing and inspection
2.3.2.1 Prototype Testing
Whether a single container or a series of containers shall be
built, prototype tests shall be carried out. As these tests should
not damage the container, no special prototype has to be built
for testing. Test requirements are given in 4.6.
2.3.2.2 Production Testing
If a series of containers shall be built, strength tests shall be
carried out on a percentage of these. Test requirements are giv-
en in 5.4.
2.3.2.3 Production Inspection
Manufacturing shall be under survey according to approved
drawings and specifications. Manufacturing inspection re-
quirements are given in 5.6.
2.4 Certification of existing containers
Existing containers that have not previously been certified ac-
cording to this Standard for Certification may in certain cases
be considered for certification. 
Containers that have been certified by other certifying bodies
will not automatically be accepted as complying with the re-
quirements in this Standard for Certification. The Society re-
serves the right to review design, inspect and test any container
before issuing the certificates described in 2.3.1 above.
All relevant available documentation shall be submitted for re-
view. If the documentation is incomplete, additional require-
ments may be specified by the society. This may include
calculations, taking out samples to determine material proper-
ties and rewelding of important welds.
Each existing container shall be thoroughly inspected,
including the use of NDT to the extent required by the survey-
or. The lifting test as described in 4.6.3.2 shall be performed.
Other tests, such as the 2-point lifting test described in 4.6.3.3
or the vertical impact test as described in 4.6.4 may in some
cases also be required.
If the container is not found to comply fully with the require-
ments of this Standard for Certification, the Society may spec-
ify required modifications, de-rating or other limitations.
2.5 Maintenance of certificate
To maintain the validity of a certificate, the container shall be
inspected annually as described in Section 9.
Such periodic inspection may be carried out by the Society or
by other inspection bodies recognized by national authorities
to carry out such inspections. However, major repairs or mod-
ifications which may alter the certificate shall be approved by
the Society.
Inspection bodies should normally meet the requirements of
ISO/IEC 17020 or equivalent standards.
Periodic inspections of offshore tank containers for dangerous
goods according to the IMDG Code can only be carried out by
DNV or other certifying bodes authorised to perform such in-
2.6 Summary of procedures
The procedures for individual and type approval are outlined
below.
Before production starts, DNV should verify the qualifications
of the manufacturer. 
Numbered certification emblems as shown in Appendix H are
allocated and distributed to the local survey office by the re-
sponsible section in DNV.
2.6.1 Procedure for individual (case-by-case) approval 
and certification
1) Application is sent through local DNV station to the ap-
proval office.
2) Order confirmed and fees agreed.
3) Drawings, documentation and calculations reviewed and
approval given by the approval office.
4) Prototype offshore container manufactured under supervi-
sion of the Society's Surveyor.
5) Container tested according to prototype test requirements,
witnessed by the Society's Surveyor. 
6) Production proceeds according to the manufacturer’s
quality plan with the necessary surveys by the Society (or
surveys according to an agreed Manufacturing Survey Ar-
rangement if applicable). Production tests according to list
in section 5.6. 
7) DNV surveyor issues Offshore Container Certificate
(form 49.07) and affixes emblem.
2.6.2 Procedure for type approval and certification
1) Application sent through local DNV station to the approv-
al office.
2) Order confirmed and fees agreed.
3) Drawings, documentation and calculations reviewed and
approval given by the approval office.
4) Prototype offshore container manufactured under supervi-
sion of the Society's Surveyor.
5) Container tested according to prototype test requirements,
witnessed by the Society's Surveyor.
6) Test report reviewed by the approval office.
7) A "Type Approval Certificate", valid for 4 years, will be
issued to the Manufacturer by the approval office.
8) Type approved offshore container entered in DNV’s reg-
ister of type approved products.
9) Production proceeds according to the manufacturer’s
quality plan with the necessary surveys by the Society (or
surveys according to an agreed Manufacturing Survey Ar-
rangement if applicable). Production tests according to list
in 5.4. 
10) DNV Surveyor issues Offshore Container Certificate
(form 49.07) and affixes emblem. 
2.6.3 Procedure for design assessment for type approval 
and certification
1) Application sent to the approval office.
2) Order confirmed and fees agreed.
3) Drawings, documentation and calculations reviewed and
approval given by the approval office.
4) A "design assessment for type approval certificate", valid
for 4 years, issued to the designer by the approval office.
A design assessment for type approval certificate enables the
DET NORSKE VERITAS
spections. designer to type approve the product with one or more manu-
Standard for Certification - 2.7-1, April 2006
Page 13facturers without repeating the design review process. in order
to obtain a "type approval certificate" and certificates for each
unit being built, the procedure described in 2.6.2, Pt.4) to
Pt.10) shall be followed. The "type approval certificate" will
contain a reference to the "design assessment for type approval
certificate".
3. Materials
3.1 Steel
3.1.1 General
Requirements for materials in lifting sets are given in 8.4.
In this section, the references to detail requirements are gener-
ally to EN standards or DNV’s “Rules for Classification of
Ships”. Other recognised standards for equivalent materials
may also be used.
The chemical composition, mechanical properties, heat treat-
ment and weldability shall be suitable for the purpose. Steels
shall comply with the material requirements of the recognised
standard and the additional requirements specified below.
Steels for welding shall be made by open hearth, the electric
furnace or the basic oxygen steel process. Steels in primary
structure shall be killed. Only materials with non-ageing prop-
erties shall be used.
Extra high strength steels, with specified yield stress above
500 N/mm2, shall not be used.
When materials of different galvanic potential are joined to-
gether, the design shall be such that galvanic corrosion is
avoided.
Welding consumables shall be according to recognized
standards for welding consumables
Tensile testing shall be carried out according to EN 10 002-1
or DNV’s “Rules for Classification of Ships” Pt.2 Ch.1 
In order to avoid initiation of brittle fracture, the steels shall
posses adequate fracture energy. Steels for primary structures
shall be tested by the Charpy impact (V-notch) method accord-
ing to EN 10 045-1 or DNV’s “Rules for Classification of
Ships” Pt.2 Ch.1.
Impact test temperatures shall be as given in Table 3-1. The re-
quirements for design temperature TD, can be seen in 4.1.4.
Requirements for impact energy depend on the specified min-
imum yield stress of the steel. The average energy absorption
for 3 base material specimens with their axis parallel to the fi-
nal rolling direction shall not be less than given in Figure 3-1.
Figure 3-1
Charpy V-notch requirements for steel
For base material specimens with their axis transverse to the fi-
nal rolling direction the requirement is 2/3 of that for longitu-
dinally oriented specimens. No single value shall be less than
70% of the required average values. If standard specimens can-
not be made, the required energy values are reduced as fol-
lows:
10 × 7.5 mm → 5/6 of above values
10 × 5.0 mm → 2/3 of above values
For steel members with thickness less than 6 mm, impact test-
ing is not required. Austenitic steels need not be impact tested.
3.1.2 Rolled, forged and cast steels in offshore container 
structures
3.1.2.1 Groups of steel
Structural steels for primary structure shall be carbon steel,
carbon-manganese steel, carbon–manganese micro-alloyed
steel or low-alloyed steel.
Rolled steel shall comply with the requirements in EN 10025
(hot rolled plates and profiles), EN 10210 or EN 10219 (hol-
low sections) or with DNV’s Rules for Classification of Ships
Pt.2 Ch.2 Sec.1 and Sec.2) and with the additional require-
ments given in this section. 
Austenitic or austenitic/ferritic stainless steels may be used,
reference EN10088 or DNV’s Rules for Classification of
Ships, Pt.2 Ch.2 Sec.2.
Plates that will be subjected to tensile loads through the thick-
ness of the plate shall comply with EN 10164 or DNV’s Rules
for Classification of Ships, Pt.2 Ch.2 Sec.1E, with quality Z25
or better.
3.1.2.2 Forged and Cast Steel 
Steel forgings shall be carbon or carbon-manganese steels.
Such forgings shall be made from killed and fine-grain treated
non-ageing steel.
For chemical and mechanical properties of alloy steel forgings,
reference shall be made to EN 10250-2, Open die steel forg-
ings for general engineering purposes — Part 2: Non-alloy
quality and special steels and to EN 10250-3, Open die steel
forgings for general engineering purposes — Part 3: Alloy
special steels, or DNV’s Rules for Classification of Ships Pt.2
Ch.2 Sec.5.
The chemical composition shall be suitable for the thickness in
question. 
Alloy steels shall be delivered in quenched and tempered con-
dition.
Steel castings shall comply with ISO 3755.
Table 3-1 Impact test temperature. Structural steel for primary 
structural members
Material thickness, t, in mm Impact test temperature in °C
t ≤ 12
12 < t ≤ 25
t > 25
TD + 10
TD
TD - 20
24
26
28
30
32
34
36
38
40
42
44
220 260 300 340 380 420 460 500
MIN. SPECIFIED YIELD STRESS, N/mm2
IM
PA
C
T 
EN
ER
G
Y 
jo
ul
e
DET NORSKE VERITAS
ISO corner fittings made from cast steel shall fulfil the require-
Standard for Certification - 2.7-1, April 2006
Page 14
ments in Table 3-2 and 3-3:
3.1.2.3 Forged bolts, nuts and pins
Bolt assemblies considered as essential for structural and oper-
ational safety shall conform to ISO 898 or other recognised
standard. Impact energy shall be documented where the bolt
size allows a Charpy-V specimen to be taken out, and shall be
a minimum of 42J at - 20° C (for sub-size specimens see 3.1.1). 
Pins used in structural connections shall conform to relevant
part of EN 10083 Quenched and tempered steels or other rec-
ognized standard.
3.2 Aluminium
The chemical composition, heat treatment, weldability and
mechanical properties shall be suitable for the purpose.
When materials of different galvanic potential are joined to-
gether, the design shall be such that galvanic corrosion is
avoided.
Aluminium used in offshore containers shall be wrought al-
loys, i.e. be made by rolling or extruding. Aluminium alloys
and tempers specified in Table 3-4 and 3-5 can be used. Use of
other alloys or tempers will be specially considered. 
3.3 Non-metallic materials
Timber, plywood, fibre reinforced plastics and other non-me-
tallic materials shall normally not be used in primary struc-
tures, but may be used in secondary structures.
Due regard shall be given to strength, durability, suitability and
possible hazards caused by use of these materials.
3.4 Material certificates
Materials used for construction of offshore containers shall be
furnished with documentation in accordance with Table 3-6.
All materials for primary structure shall be identifiable against
the certificates.
4. Design 
4.1 General
An offshore container shall have sufficient strength to allow
loading and unloading in open seas from a ship deck with a sea
state up to significant wave heights of 6 m. Consideration shall
be given in the design to local impact loads, e.g. from hitting
other deck cargo or rigid parts of the ship structure, which may
Table 3-2 Chemical composition (ladle analysis) 1)
Chemical composition %
C
max.
Mn Si
max.
P
max.
S
max.
Cr
max.
Ni max. Cu
max.
Mo
max.
Al 2)
min
Cr+Ni+Cu+Mo
max.
0.20 0.90 to 1.50 0.50 0.035 0.035 0.25 0.30 0.20 0.08 0.015 0.70
1) The carbon equivalent Ceq = C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15 (%) shall not exceed 0.45 %
2) other grain refiners may be accepted
Table 3-3 Mechanical properties
Yield
Strength
Re 
min.
N/mm2 
Tensile 
Strength
Rm
N/mm2
Elongation
A5
min.
%
Reduction
of area
Z
min.
%
Impact energy
KV 
at -20°C
min.
joule
220 430 to 600 25 40 27
Table 3-4 Aluminium alloys and tempers for rolled products
Alloy Temper Yield strength 
(N/mm2)
Tensile 
strength 
Rm mini-
mum or 
range
(N/mm2)
ISO 209-1 AA1) ISO/ AA Delivery 
condition2)
(Rp0.2)
Welded
(HAZ)
AlMg2.5 5052 0/0
HAR/H32
HBR/H34
65
130
150
65
65
65
165-215
210-260
230-280
AlMg3 5754 0/0
HAR/H32
HBR/H34
80
130
160
80
80
80
190-240
220-270
240-280
AlMg3.55154A 0/0
HAR/H32
HBR/H34
85
180
200
85
85
85
215-275
250-305
270-325
AlMg4 5086 0/0
HAR/H32
HBR/H34
100
185
220
100
100
100
240-310
275-335
300-360
AlMg3Mn 5454 0/0
HAR/H32
HBR/H34
85
180
200
85
85
85
215-285
250-305
270-325
AlMg4.5Mn 5083 0/0
HAR/H32
125
215
125
125
275-350
305-380
Table 3-5 Aluminium alloys and tempers for extruded products
Alloy Temper Yield strength 
(N/mm2)
Tensile 
strength 
Rm mini-
mum or 
range 
(N/mm2)
ISO 209-1 AA1) ISO/AA Delivery 
condition2) 
(Rp0.2)
Welded
(HAZ)
AlSi0.5Mg 6063 TB/T4
TF/T6
65
170
65
65
130
205
AlSi1MgMn 6082 TB/T4
TF/T6
TF/T6
110
250 (for t ≤ 5 mm)
260 (for t > 5 mm)
110
110
110
205
290
310
1) AA = American Aluminium Association
2) In calculations, yield strength is not to exceed 70% of ultimate ten-
sile strength
Table 3-6 Documentation of materials
Structure Minimum documentation requirementsa)
Inspection 
Certificate 
Type 3.2b)
Inspection 
Certificate Type 
3.1c)
Test Report 
Type 2.2
ISO-corner 
fittings
X 
Pad eyes X
Other primary 
structural 
members
X
Secondary 
structural 
members
X
a) Material documentation as defined in EN 10204 (2004)
b) Certificate issued by DNV or other recognized certifying body. 
(Equivalent to 3.1C in ISO 10474)
c) Certificate issued by the manufacturer (Equivalent to 3.1B in 
ISO 10474)
DET NORSKE VERITAS
cause extreme loads in such conditions.
Standard for Certification - 2.7-1, April 2006
Page 15
Guidance note 1:
For containers with special features, additional design require-
ments may be applicable. Such special features many be related
to e.g. additional fittings for other methods of handling or ther-
mal containers with refrigeration machinery, etc.
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Guidance note 2:
If equipment carried in or installed in an offshore container can
not withstand the lifting or shock loads, such equipment should
be protected or supported on dampers, or the container should be
handled only when conditions allow.
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Guidance note 3:
For service containers, it is recommended that the rating, R, is
chosen higher than the estimated fitted out mass, i.e. to specify a
certain payload even if the container is not intended to carry car-
go. This will allow for changes in the amount and mass of equip-
ment fitted in a service container during its operational life, and
it will enable the container to carry a certain amount of non-per-
manent equipment.
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Guidance note 4:
For containers with exposed aluminium, the danger of sparks
caused by the impact of aluminium against corroded steel (ther-
mite reactions) should be taken into account. National authorities
may have restrictions on the use of aluminium containers on off-
shore installations.
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4.1.1 Structural design
Containers shall be designed as structural frames (primary
structure), with non-load bearing cladding where necessary
(secondary structure). Only the primary structure shall be con-
sidered in the design calculations.
However, on waste skips with trapezium shaped sides and with
open top or only a non-stressed cover above the bracing where
the pad eyes are attached, the whole structure may be consid-
ered as primary structure, and the skip may be calculated as a
monocoque construction.
All connections between frame members and between pad
eyes and frame members shall be designed to give good conti-
nuity. Where beams of different cross sections meet, they shall
normally be aligned as far as possible, and measures shall be
taken to minimize stress concentrations on webs or flanges.
Offshore containers may be constructed with partly removable
primary structure. Bolted or pinned connections will be spe-
cially considered with regard both to strength and securing.
Removable beams, walls or covers shall be secured in such a
way that they will not fall off even if a securing device is dam-
aged
4.1.2 Stability against tipping
To prevent the containers from overturning (tipping) on a mov-
ing deck, they shall be designed to withstand 30° tilting in any
direction without overturning. Cargo may be assumed evenly
distributed with centre of gravity at the half height of the con-
tainer. For dedicated purpose containers with a fixed centre of
gravity (e.g. bottle racks, service containers or tank containers)
the actual centre of gravity shall be used. If the stability of a
container can not be verified through calculations, DNV may
require a tilting test, see 4.6.5.
4.1.3 Protruding parts and top protection
Protruding parts on the outside of the container frame that may
catch or damage other containers or structures shall be avoid-
consideration. Protective structure or deflector plates may be
required at protrusions.
Doors, handles, hatch cleats etc. shall be so placed or protected
that they do not catch the lifting set.
Supporting pads and fork pockets may protrude below the bot-
tom frame of containers, but shall have deflector plates to pre-
vent snagging.
Guidance note:
Deflector plates should be designed such that the angle between
the outer plane (e.g. of bottom rail or wall) and the free edge of
the plate is not more than 35°. Deflector plates on the underside
of the container should be placed at, or as near as practical to, the
outer edges of the container.
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Padeyes may protrude above the top level of the container
frame (see also 4.4.1). 
Stacking fittings and guides that protrude above the top of the
container frame shall be designed such that the risk of damage
to other containers or cargoes from these during lifting opera-
tions is minimized. They shall also be designed such that dam-
ages to the stacking fittings does not cause damage to the
padeyes.
Parts of the permanently attached lifting sets will often hang
over the side of the top frame. If containers are designed for
stacking, the corners shall be raised above the frame and roof
sufficiently to prevent damage to the lifting set.
The top of all open frame containers and of all open top con-
tainers with permanent internal fittings, machinery or other in-
stallations where crane hooks or forerunners may snag, shall
be protected with grating or plates. This may be fixed, hinged
or removable. Top protection shall be capable of being se-
cured.
4.1.4 Design temperature
The design air temperature, TD, shall not be taken higher than
the (statistically) lowest daily mean temperature for the area
where the offshore container shall operate and shall not be
higher than - 20°C.
For containers that are exclusively to be used in areas with
temperate climate see Annex 3.
4.2 Structural strength
The required strength of a container is found by calculations
and verified by prototype tests, as described in section 4.6. 
Guidance note:
Calculation methods may be:
— manual
— using DNV’s OffCon program as an aid (This program is
available to customers on DNV’s Website www.dnv.com)
— 2- or 3-dimensional frame analysis
— Finite Element Methods (on whole frame or special areas,
e.g. pad eyes)
See Appendix C for advice on these methods.
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4.2.1 Allowable stresses
For the design loads defined in the following, no equivalent
stress level shall (unless otherwise specified) exceed:
σe = 0.85 × C
where σe is the Von Mises equivalent stress and C is defined
below:
For steel: 
C = R 
DET NORSKE VERITAS
ed. Minor protrusions on the sides may be allowed after special e
Standard for Certification - 2.7-1, April 2006
Page 16
For aluminium:
Base material: 
C = Rp0.2 but not to be takengreater than 0.7 × Rm
Weld and heat affected zone: 
C = yield strength in the weld and heat affected zone 
See Tables 3-4 and 3-5 for yield strength of the approved alu-
minium qualities.
Note:
The strength of aluminium alloys is considerably reduced in
welds and heat affected zones. The reduction depends on materi-
al properties, initial tempering and type of product (rolled, ex-
truded). Materials not listed in Tables 3-4 and 3-5 will be
considered in each case.
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4.2.2 Load distribution
In these calculations, internal loads shall be assumed evenly
distributed on the offshore container floor. For tank containers,
other containers with permanently mounted heavy equipment
and for dedicated purpose containers, the actual distribution of
the internal load shall be used in the calculations. 
4.2.3 Lifting loads
4.2.3.1 Lifting with lifting set
The design load on the primary structure shall be taken as:
FL = 2.5 × R × g
To achieve this the internal load shall be taken as Fi = (2.5 x R-
T) × g, 
Note:
Calculated deflections should be checked. Reference is made to
allowable deflections in prototype tests, see 4.6.3.2.
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Pad eyes shall be designed for a total vertical load of: 
The load Fp shall be considered as being evenly distributed be-
tween (n - 1) pad eyes where n is the actual number of pad eyes.
For calculation purposes n shall not exceed 4 or be less than 2.
To find resulting sling force on the pad eyes, the sling angle
must be taken into account. Hence, the resulting sling load
(RSL) on each pad eye will be:
where v is the angle between a sling leg and the vertical, as-
sumed to be 45° unless a smaller angle is specified.
Guidance note 1:
Containers without roof may have insufficient strength and stiff-
ness to pass the 2 point lifting test (4.6.3.3). In order to avoid
building prototypes that will not pass the test, the ability of an
open top container to withstand the load occurring in the 2-point
lifting test should be checked by a suitable calculation method.
In these calculations, the nominal yield stress, Re, of the material
should not be exceeded. The calculations do not replace proto-
type testing.
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Guidance note 2:
Containers can be excessively flexible without having high cal-
to verify that the deflections (both maximum and relative) will be
acceptable.
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Containers with only a single pad eye may be approved after
special consideration. The design load for such a pad eye shall
be taken as:
For requirements for lifting sets, see Section 8.
4.2.3.2 Lifting with fork lift truck
The mass of the lifting set, S, shall be taken into account when
calculating the strength of the fork pockets.
Guidance note:
If S is not known, an estimated mass of the lifting set may be used
in the calculations.
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The design load on the primary structure shall be taken as:
FF = 1.6 × (R + S) × g
To achieve this, the internal load shall be taken as:
Fi = [1.6 × (R + S)-T] × g
Where fork pockets are only intended for empty handling of
the container, the design load shall be taken as FF = 1.6 × (T+S)
× g. For marking of containers with such pockets see 6.1.
4.2.4 Impact loads
Impact loads are dynamic loads of very short duration. Ideally,
dynamic calculations or tests should be carried out. However,
for most applications it is sufficient to carry out simplified stat-
ic calculations as outlined below to verify the local strength,
and to perform a vertical impact test (see 4.6.4) to verify the
container’s overall ability to withstand such loads.
When simplified calculations are used, and each beam is con-
sidered separately, due consideration shall be given to the sup-
port conditions for this beam.
4.2.4.1 Horizontal impact
The main frame structure shall be dimensioned to withstand a
local horizontal impact force acting at any point. This force
may act in any horizontal direction on the corner post. On all
other frame members in the sides the load may be considered
as acting at right angles to the side. Where relevant, the calcu-
lated stresses shall be combined with lifting stresses. However,
only stresses resulting from static lifting loads (R g) need to be
considered.
The following values shall be used for the static equivalents to
an impact load:
FHI = 0.25 × R × g for corner posts
FHI = 0.25 × R × g for side rails of the bottom structure
FHI = 0.15 × R × g for other frame members of the side struc-
ture, including the top rails
Calculated equivalent stresses shall not exceed:
σe = C
C is defined in section 4.2.1
Maximum calculated deflections with these loads shall not ex-
ceed:
where:
For corner posts and bottom side rails: 
l = the total length of the rail or post.
F R gp = × ×3
vn
gRRSL
cos)1(
3
×−
××=
F R gp = × ×5
y = ln
250
DET NORSKE VERITAS
culated stresses. These calculations should therefore also be used n
Standard for Certification - 2.7-1, April 2006
Page 17
For other frame members:
ln = the length of the shortest edge of the wall being considered
For horizontal impact on tank containers for dangerous car-
goes see also 4.5.2.1.
4.2.4.2 Vertical impact
Maximum vertical impact forces are likely to occur when a
container is lowered down to a heaving ship deck. If the deck
is at an angle, the first impact will be on a corner. Such impact
forces can not readily be simulated by static forces. As dynam-
ic calculations will be very complex, it is usually sufficient to
verify the strength by a vertical impact test as described in
4.6.4.
In addition, the side rails and end rails in the bottom shall be
able to withstand vertical point forces at the centre span of:
FVI = 0.25 × R × g
Calculated equivalent stresses shall not exceed:
σe = C
C is defined in section 4.2.1.
Calculated deflections shall not exceed
where:
ln = the total length of the rail.
4.2.5 Minimum material thickness
The following minimum material thickness requirements ap-
ply:
a) Those parts of corner posts and bottom rails forming the
outside of a container: t ≥ 6 mm.
However, for containers with a max. gross mass R ≤ 1000
kg the minimum material thickness shall be 4 mm.
b) All other parts of primary structure: t ≥ 4mm.
c) Secondary structure made from metallic materials: t = 2
mm. Secondary structural components used only for pro-
tection (e.g. of tanks) must however have sufficient thick-
ness to give adequate protection.
d) On waste skips of monocoque design (see 1.4.1c) the min-
imum thickness within an area of 100 mm from the side
edges shall be 6 mm. The remaining parts of the side and
bottom structure shall be min. 4 mm.
Note:
The thickness both of primary and secondary structure may have
to be increased beyond these values after special considerations.
Such considerations may include material used, rating, design,
function of the structural component and corrosion allowances.
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4.3 Welding
4.3.1 Welding of padeyes
All main welds between pad eyes and the primary frame struc-
ture shall always be full penetration welds.
Guidance note:
Fillet welding of additional supporting welds on pad eyes and on
Padeye supporting structure may be acceptable after special con-
sideration.
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4.3.2 Welding of other primary structure
Essential and non-redundant primary structural members shall
Fork pockets shall be connected to the bottom rails with full pen-
etration welds, but if the fork pockets pass through the bottom
rail, fillet welds may be used. For other primary structure, fillet
welds may be permitted after special agreement with the Society.
Welding of secondary structure